Microwaves are used, for example, in semiconductor processing to anneal, clean, cure, and degas. The microwaves can be used to process a single wafer and/or multiple wafers in a batch. The microwaves are generated and a waveguide is used to transmit the microwaves into a cavity. The cavity and any wafer supports or other structures inside the cavity affect the distribution of the microwaves. Standing waves can be formed in the cavity or the microwave distribution could be non-uniform. Both standing waves and non-uniformity will have a negative effect on the processing of the wafer in the cavity.
Accordingly, the inventors have developed an improved microwave detector and method of detecting microwaves in a cavity.